Summary Impact Type

Research Subject Area(s)

Download original

Summary of the impact

The parasite Neospora caninum is the leading cause of abortion in
cattle in the UK, resulting in
around 6,000 abortions per year; and a $1.3b pa international problem.
There are no effective
drugs or vaccines to control neosporosis. University of Liverpool (UoL)
research on the
development of diagnostic tests, understanding the pathogenesis,
epidemiology and transmission
of N. caninum has made an important contribution to developing
best practise herd health
schemes, now offered by the Animal Health and Veterinary Laboratories
Agency (AHVLA) and by
a commercial company `myhealthyherd', to eradicate N. caninum
infection from a herd. This has
enabled cattle farmers to improve their businesses by reducing abortion
rates and other costs
associated with neosporosis.

Underpinning research

N. caninum is an important protozoan parasite infecting cattle and
dogs. It has its most serious
effects in cattle where it is considered responsible for 6,000 abortions
per year in England and
Wales alone. Worldwide farming losses in 2013 were estimated to be $1.3b;
two thirds of those
losses occurring in dairy cattle and one third in beef. In dairy cattle,
global data indicates that 16%
of dairy cattle are seropositive, that figure rising to over 40% in
aborting cows.

Research on neosporosis at the UoL was initiated by Professor Sandy Trees
(retired 2011), who
isolated N. caninum for the first time in Europe; a description of
this isolate was published in 1995
and led to development of a diagnostic ELISA [1]. This serological test
was aimed specifically at
diagnosing Neospora-associated abortions, but was adapted and
validated by UoL for surveillance
purposes and subsequent epidemiological work stemmed from development and
application of this
test.

The serological ELISA test was commercialised in collaboration with a
local Merseyside
biotechnology company (Mast Diagnostics) and adopted by AHVLA in 1999.
Between 1996 and
2010, with funding from several sources including industry, all listed in
section 3, UoL Professors
Sandy Trees and Diana Williams (1994-present) produced the first analysis
of the relative
importance of vertical transmission compared to post-natal infection of
cattle by showing that in
normally calving N. caninum infected cattle, transplacental
transmission occurred in 95% of
pregnancies, and that an infected animal was 7 times more likely to abort
compared to uninfected
cattle [2].

In 1999, the UoL group showed that most infected cattle harbour chronic
infections, most likely to
have been acquired congenitally and that post-natal infection was a
relatively rare event. UoL
research followed this up in 2009 by demonstrating that abortion storms
associated with N.
caninum are more likely to be associated with post-natal exposure of
pregnant cattle to oocyst
infection [6], complementing a prior study in 2007 which showed that
oocyst infection could lead to
exogenous transplacental transmission (with or without abortion) but
significantly did not lead to
persistent infections and subsequent endogenous transplacental
transmission [5].

The group developed an experimental challenge system to test the efficacy
of potential vaccines in
protecting against abortion, developing a highly effective but not
commercially viable live vaccine
[3,4]. Using this experimental challenge system and infecting cattle at
different times during
gestation, research showed that the parasite was more likely to cause
abortion early in gestation
and that this is linked to foetal immuno-competence.

Details of the impact

The Liverpool team has used their research findings to create significant
economic benefits for the
UK's cattle industry by collaborating directly with AHVLA and
Myhealthyherd to design herd health
schemes to reduce the economic impact of N. caninum. The main
beneficiaries of the research are
UK dairy farmers, who now have access to information, which enables them
to control the disease
in their herds and mitigate the massive economic and emotional impact of
an outbreak of
neosporosis.

Research conducted by the Liverpool team has led to a better
understanding of the
immunopathogenesis, life cycle and transmission of the parasite together
with improved,
commercially available diagnostics. As a consequence, as key participants
in AHVLA working
groups, Williams and Trees were involved in designing herd health schemes
to improve control of
disease. In 2008/9, two schemes were launched, one a commercial scheme,
Myhealthyherd, and
the other, AHVLA's Herdsure scheme [7], both based on advice on reducing
transmission built on
research done at University of Liverpool. A series of roadshows, delivered
by Professor Trees in
2008-9 was used to publicise these accreditation schemes. To ensure the
widest possible reach,
these DEFRA funded roadshows targeted hundreds of veterinarians each of
whom were asked to
hold multiple farmer meetings. These schemes focus on identifying infected
animals within a herd
and strategically managing breeding programmes and heifer replacement
regimes to reduce the
number of infected cows entering the milking herd. Within these
programmes, regular nationwide
surveillance using bulk tank milk antibody tests are used to monitor
levels of N. caninum infection
within herds typically through NMR/NML. Biosecurity measures including
quarantine testing,
control of dogs on the farm and covering feed stores to reduce risk of
contamination are
recommended to control the spread of infection. There has been widespread
publicity and it has
even featured on the popular BBC 4 soap opera, the Archers.

The team's research into abortion storms and quantifying the risk of
post-natal exposure to
infection have led to an increase in our understanding of frequency of
different routes of
transmission of Neospora. In addition, advisory meetings were held
with AHVLA in 2008 to assist
in developing its herd health farm assurance scheme prior to its launch in
2009/10. Information
about these two schemes are disseminated to dairy farmers through the
farming press, advisory
information sent out by AHVLA and through a private scheme with a
dedicated website. The
Herdsure Neospora protocol has also been accepted under the CHeCS scheme
(Cattle Health
Certification Standards; an organisation owned by the BCVA, National
Cattle Association (dairy),
the National Beef Association and Holstein UK [8].

Beneficiaries of these health schemes are dairy farmers in UK. Effective
measures to reduce
levels of infection within the herd, to protect cows from introduction of
N. caninum into the herd,
through biosecurity measures and to reduce the potential of spread within
the herd via dogs, the
definitive host for the parasite, all contribute to reducing abortion
rates and other costs, such as
reduced fertility, associated with neosporosis. By obtaining herd health
accreditation or joining
`myhealthyherd,' farmers can create their own herd health plans in
conjunction with their vets,
manage infectious disease, work out profit opportunities and obtain a
Health Visa or herdhealth
accreditation, to maximise the sale value of stock. To date, over 5,000
farms now use
"Myhealthyherd" in England and Wales - to provide context there are c
14,500 dairy farms in the
UK. The knowledge gained from UoL research, together with outputs from
other groups, has had
an impact on control of neosporosis worldwide.

Sources to corroborate the impact

Each source listed below provides evidence for the corresponding numbered
claim made in section
4 (details of the impact).